Identification of Xanthomanas axonopodis pv. vesicatoria, causal agent of bacterial spot disease of pepper, and studies on biological control of the disease by plant growth promoting rhizobacteria

ABSTRACT PhD THESIS IDENTIFICATION OF Xanthoma» as axonopodts pv. vesicatoria, CAUSAL AGENT OF BACTERIAL SPOT DISEASE OF PEPPER, AND STUDIES ON BIOLOGICAL CONTROL OF THE DISEASE BY PLANT GROWTH PROMOTING RHIZOBACTERIA Mustafa MÎRİK DEPERTMENT OF PLANT PROTECTION INSTITUTE OF NATURAL AND APPLIED SCIENCES UNIVERSITY OF ÇUKUROVA Supervisor: Prof. Dr. Ozden CINAR Year:2005, Page:162 Jury: Prof. Dr. Ozden CINAR Prof. Dr. Hikmet SAYGILI Associated Prof. Dr. Fikrettin SAHIN Associated Prof. Dr. Yeşim AYSAN Assistant Prof. Dr. Soner SOYLU Bacterial strains, isolated from diseased pepper plants in commercial fields of the eastern Mediterranean region in Turkey, identified as Xanthomonas axonopodis pv vesicatoria (Xav) by physiological, biochemical, DAS-ELISA, PCR and FAMEs analysis. In the present study, possibility of biological control of the disease by pant growth promoting rhizobacteria (PGPR) was investigated as an alternative method to chemical applications. 187 bacterial strains were isolated from soil and pepper roots in Adana, Mersin, Osmaniye, Kahramanmaraş and Hatay cities. Eleven phosphate solublizing bacteria were selected as candidate PGPR Selected three bacterial strains and their combination as PGPR were used in pot and field experiments. PGPR applications significantly reduced disease incidence on pepper plants (average 65%), and increased plant growth (plant length, stem diameter, plant weight, dried weight, root length, root dried weight, yield, fruit length and fruit weight) at different rates compared with control. PGPR strains used in this study were identified as Bacillus megatarium by FAME analysis. Key words: bacterial spot disease, DAS-ELISA, PCR, biological control, antagonist. II